Concrete mixing drums, particularly those mounted on trucks for delivery of large quantities of concrete to remote sites are susceptible to concrete build-up on the interior surface of the drums. Even though these mixing drums are constantly rotated, thereby mixing the concrete contained within, a portion of concrete eventually hardens and sticks to the inside surfaces of the drum. Once this process starts, more and more concrete adheres to the drum sides, until the concrete build-up is significant.
In concrete trucks, any concrete build-up in the drum reduces the amount of usable concrete that may be contained within the drum, thereby reducing delivery efficiency and therefore the cost of delivery. In large-scale application this reduction in efficiency can become quite costly. Furthermore, the concrete build-up tends to cause more build-up, thereby exacerbating the problem progressively over time. Thus many trucks carry a build-up of “dead” concrete which makes the trucks heavier and able to hold less good product. These problems lead to decreased fuel economy and transportation inefficiency and therefore cause many companies to incur great expense to rectify theses problems.
To combat concrete build-up mix drums must be cleaned periodically to remove the hardened concrete from the drum interior surfaces. In some applications, the interior of the drum is accessed through a side access door, and cleaning personnel enter the interior of the drum with high pressure water hoses and hand tools to spray and chisel the concrete from the drum surfaces. This technique is quite obviously labor intensive, as well as being hazardous to cleaning personnel. Some concrete companies no longer even permit entry into mixing drums in this fashion, necessitating the need for alternative cleaning techniques.
Accordingly, some prior art pressure washing systems have been developed that utilize high pressure water nozzles that are positioned within the drum, typically through an opening in the rear of the drum, to spray the interior surfaces of the drum with high pressure wash water to dislodge the hardened concrete from the interior surfaces. Many of these prior art devices employ expensive nozzles for spraying high pressure water, as well as complex sensor systems to insure that the spray nozzle doesn't impact any portion of the drum interior. Typically, the spray nozzles and a proximity sensor are secured to the end of a boom that extends inwardly into the drum and is then retracted as the cleaning is finished.
However, many of the prior art systems are highly complex and prone to breakdown, since the sensors and other components that must be inserted into the drum are located on the end of the boom and are thus exposed to water and concrete. The cleaning environment is extremely abusive to these components, since clumps of concrete often fall into the drum, as well as the obvious moisture present in the interior of the drum. Furthermore, in order to provide for even cleaning of the drum, the boom must be carefully positioned to enter through a hole in the rear of the drum once the loading hopper is removed or detached, so that the longitudinal axis of the boom must be carefully aligned with the axis of the drum to avoid the nozzle hitting the sides of the drum as it advances.
This careful alignment of the boom, as well as the necessity for removing the loading hopper prior to the procedure is very labor intensive. Accordingly, this procedure is usually undertaken infrequently, and as such is very time-consuming and difficult, since the concrete build-up in the drum interior is often very thick before this procedure is even attempted.
Accordingly, there is a need in the art for a wash system for a concrete mixer that is easy and relatively quick to use so that daily wash of the drum may occur.
Other features, object and advantages of the present invention will become apparent from the detailed description of the preferred embodiment(s) taken in conjunction with the drawing Figures.